The present invention relates to a content transmission apparatus, a content reception apparatus and a content transmission method that are suitable typically for protecting copyrights of video and audio contents transmitted and received thereby through a network.
With improvement of the processing power of a personal computer (abbreviated hereafter to a PC), the processing speed and the storage capacity of a hard-disk drive (abbreviated hereafter to an HDD) embedded in the PC also increase as well. By the processing power of a PC, the processing speed and storage capacity of the PC are implied. In this situation, even a PC of a rank intended for an ordinary home can be used for recording a TV broadcast program in the HDD to be watched later through a display unit of the PC.
In addition, with the decreasing price of the HDD having a large storage capacity, an HDD video-recording apparatus having such an HDD embedded therein has been introduced also as a home video-recording apparatus for digitally recording audio/video information, and the fact that the user can utilize such a video-recording apparatus with a high degree of convenience by making use of a disk as a recording medium attracts much attention. In recording equipment such as a video-recording apparatus and a PC, which employ the HDD described above, audio/video information can be recorded in an HDD fixed in the recording equipment in a room of a home. Thus, if a user wants to watch the recorded information in another room of the home, the user must move the recording equipment itself to the other room. That is to say, it is difficult to implement an application in which a plurality of video-recording/reproduction apparatuses employing a replaceable recording medium is provided and the audio/video medium is moved from a video-recording/reproduction apparatus installed in a room to another apparatus installed in another room. An example of the video-recording/reproduction apparatus employing a replaceable recording medium is a VTR.
In order to solve the problem described above, there has been conceived a solution in which a video-recording apparatus is provided with an interface with a wire or radio LAN (Local Area Network) and, by transmitting audio/video information recorded at a room of a home from the video-recording apparatus to another PC or reception apparatus installed at any other room of the home by way of the network, the user can watch the recorded information in the other room.
By the way, in order to protect copyrights of information such as contents, a Digital Transmission Content Protection (DTCP) has been provided as a typical copy protection method incorporated in a digital AV apparatus. The DTCP defines a copy protection method on an IEEE1394 bus or the like. For more information on the DTCP, refer to non-patent reference 1, namely, the 5C Digital Transmission Content Protection White Paper authored by Hitachi Ltd., et cetera.
In addition, some technologies have been developed as technologies for implementing copy protection to protect copyrights in the course of transmission between apparatus or transmission through a network. Such technologies are disclosed in documents such as Japanese Patent Laid-open No. 2000-287192 referred to hereafter as patent reference 1 and Japanese Patent Laid-open No. 2001-358706 referred to hereafter as patent reference 2.